Presently certain radiation responsive systems such as conventional heat seeking missiles are extremely effective against "hot targets," targets which passively emit strongly in the infrared spectral region. However, these same systems are ineffective against "cold targets" which must be tracked in conjunction with a target designating laser. On the other hand radiation responsive systems designed for use in conjunction with a target designating laser for tracking "cold targets" are ineffective for tracking "hot targets" when no laser target designator is used. Accordingly, separate systems must be employed for tracking "hot targets" and for use in conjunction with laser designated "cold targets."